The present invention concerns therapeutic compositions and methods for the treatment of restenosis and cancer.
The following is a brief description of the physiology, cellular pathology and treatment of restenosis. The discussion is not meant to be complete and is provided only for understanding of the invention that follows. This summary is not an admission that any of the work described below is prior art to the claimed invention.
Coronary angioplasty is one of the major surgical treatments for heart disease. Its use has been accelerating rapidly; over 450,000 procedures are performed in the U.S. annually. The short term success rate of angioplasty is 80 to 90%. However, in spite of a number of technical improvements in the procedure, post-operative occlusions of the arteries, or restenosis, still occur. Thirty-five to forty-five percent of patients who have undergone a single vessel angioplasty develop clinically significant restenosis within 6 months of the procedure. The rate of restenosis is even higher (50 to 60%) in patients who have undergone multivessel angioplasty (Califf, R. M., et al., 1990, in Textbook of Interventional Cardiology., E. J. Topol, ed., W. B. Saunders, Philadelphia, pp 363-394.).
Histopathological studies have shown that restenosis after angioplasty is characterized by migration of medial smooth muscle cells to the intima and a striking hyper-proliferative response of these neointimal cells (Garratt, K. N., et al., 1991, J. Am. Coll. Cardio., 17, 442-428; Austin, G. E., et al., 1985, J. Am. Coll. Cardiol., 6, 369-375). Smooth muscle cell proliferation could be an overly robust response to injury. Alternatively, the intimal smooth muscle cells within atherosclerotic lesions are already in an activated or "synthetic" state (Sjolund, M., et al., 1988, J. Cell. Biol., 106, 403-413 and thus may be poised to proliferate. One recent study demonstrated a positive correlation between the presence of activated smooth muscle cells in coronary lesions and the extent of subsequent luminal narrowing after atherectomy (Simons, M., et al., 1993, New Engl. J. Med., 328, 608-613). In any case, slowing smooth muscle cell proliferation after angioplasty could prevent intimal thickening and restenosis.
The presently preferred therapeutic treatment for restenosis is the use of streptokinase, urokinase or other thrombolytic compounds, such as fish oil, anticoagulants, ACE (angiotensin converting enzyme) inhibitors, aspirin and cholesterol lowering compounds. Alternative treatment includes the surgical incorporation of endoluminal stents. The occurrence of pharmacologic side-effects (particularly bleeding disorders associated with anti-coagulants and platelet inhibitors) is an issue with current therapies. Popoma, J. J., et al., report that the current therapies have not significantly impacted the rates of restenosis occurrence. (Circulation, 84, 1426-1436, 1991).
Recently, the results of a clinical trial of the efficacy of an anti-platelet therapy have been reported. Patients undergoing coronary angioplasty were given a single bolus injection followed by a 12 hour infusion of an antibody directed against the platelet adhesion molecule, gpllb/gpllla. After six months, patients with the treatment showed a 23% reduction in the occurrence of restenosis than patients receiving placebo (27 vs. 35%; p=0.001).
A number of growth factors have been shown to induce smooth muscle cell proliferation. In vitro, platelet-derived growth factor (PDGF) is a potent smooth muscle cell mitogen (Ross, R., et al., 1974, Proc. Natl. Acad. Sci. USA, 71, 1207-1210) and a smooth muscle cell chemoattractant (Grotendorst, G., et al., 1982, Proc. Natl. Acad. Sci. USA, 71, 3669-3672.). In vivo, when PDGF is expressed ectopically in porcine arteries, it induces intimal hyperplasia (Nabel, E. B., et al., 1993, J. Clin. Invest., 91, 1822-1829). Furthermore, antibodies to PDGF have been shown to reduce intimal thickening after arterial injury (Ferns, G. A. A., et al., 1991, Science, 253, 1129-1132). Analysis of .sup.3 H-thymidine incorporation in the lesions indicates that the anti-PDGF antibodies primarily inhibit smooth muscle cell migration.
Basic fibroblast growth factor (bFGF) is another smooth muscle cell mitogen in vitro (Klagsbrun, M. and Edelman, E. R., 1989, Arteriosclerosis, 9, 269-278). In a rat model, anti-bFGF antibodies inhibit the proliferation of medial smooth muscle cells 24 to 48 hours after balloon catheter injury (Lidner, V. and Reidy, M. A., 1991, Proc. Natl. Acad. Sci. USA, 88, 3739-3743). In addition to bFGF, heparin binding epidermal growth factor (HB-EGF) (Higashiyama, S., et al., 1991, Science, 251, 936-939.), insulin-like growth factor I (IGF-I) (Banskota, N. K., et al., 1989, Molec. Endocrinol., 3, 1183-1190) and endothelin (Komuro, I., et al., 1988, FEBS Letters, 238, 249-252) have been shown to induce smooth muscle cell proliferation. A number of other factors (such as interleukin-1 and tumor necrosis factor-.alpha.) may indirectly affect smooth muscle cell proliferation by inducing the expression of PDGF (Hajjar, K. A., et al., 1987, J. Exp. Med., 166, 235-245; Raines, E. W., et al., 1989, Science, 243, 393-396).
When whole serum is added to serum-starved smooth muscle cells in vitro, the oncogenes, c-myc, c-fos, and c-myb, are induced (Kindy, M. S. and Sonenshein, G. E., 1986, J. Biol. Chem., 261, 12865-12868; Brown, K. E., et al., 1992, J. Biol. Chem., 267, 4625-4630) and cell proliferation ensues. Blocking c-myb with an antisense oligonucleotide prevents cells from entering S phase (Brown, K. E., et al., 1992, J. Biol. Chem., 267, 4625-4630.). Thus, c-myb is required for the G.sub.1 to S transition after stimulation by the multitude of growth factors present in serum. In vivo, a c-myb antisense oligonucleotide inhibits restenosis when applied to rat arteries after balloon angioplasty (Simons, M., et al., 1992, Nature, 359, 67-70). Similarly, an antisense oligonucleotide directed against mRNA of the oncogene c-myc was shown to inhibit human smooth muscle cell proliferation (Shi, Y., et al., 1993, Circulation, 88, 1190-5) and migration (Biro, S., et al., 1993, Proc. Natl. Acad. Sci. U S A, 90, 654-8).
Ohno et al., 1994 Science 265, 781, have shown that a combination of viral thymidine kinase enzyme expression (gene therapy) and treatment with anti-viral drug ganciclovir inhibits smooth muscle cell proliferation in pigs, following baloon angioplasty.
Epstein et al., "Inhibition of non-transformed cell proliferation using antisense oligonucleotides," NTIS publication 1992 discusses use of antisense oligonucleotides to c-myc, PCNA or cyclin B. Fung et al., PCT WO91/15580, describes gene therapy for cell proliferative disease and mentions administration of a ribozyme construct against a PGR element. Mention is made of inactivation of c-myb. Rosenberg et al., WO93/08845, Calabretta et al., WO92/20348 and Gewirtz WO93/09789 concern c-myb antisense oligonucleotides for treatment of melanoma or colorectal cancer, and administration locally. Sytkowski, PCT WO 93/02654, describe the uses of antisense oligonucleotides to inhibit c-myb gene expression in red blood cells to stimulate hemoglobin synthesis.
Nabel and Nabel, U.S. Pat. No. 5,328,470, describe a method for the treatment of diseases by delivering therapeutic reagents directly to the sites of disease. They state that--
" . . . Method is based on the delivery of proteins by catheterization to discrete blood vessel segments using genetically modified or normal cells or other vector systems . . . In addition,, catalytic RNAs, called ribozymes, can specifically degrade RNA sequences. . . . The requirements for a successful RNA cleavage include a hammerhead structure with conserved RNA sequence at the region flanking this structure . . . any GUG sequence within the RNA transcript can serve as a target for degradation by the ribozyme . . . gene transfer using vectors expressing such proteins as tPA for the treatment of thrombosis and restenosis, anglogenesis or growth factors for the purpose of revascularization . . . "